Thin-film resistor and method for producing the same

Abstract

Provided is a thin-film resistor that has a higher resistance value than the conventional thin-film resistors while retaining excellent TCR characteristics. The thin-film resistor includes a substrate, a pair of electrodes formed on the substrate, and a resistive film connected to the pair of electrodes. The resistive film includes a first resistive film and a second resistive film, the second resistive film having a different TCR from that of the first resistive film, and each of the first resistive film and the second resistive film contains Si, Cr, and N as the main components.

What is claimed is: 
     
       1. A thin-film resistor comprising a substrate, a pair of electrodes formed on the substrate, and a resistive film connected to the pair of electrodes, wherein
 the resistive film includes a first resistive film and a second resistive film, the second resistive film having a different TCR from that of the first resistive film, and 
 each of the first resistive film and the second resistive film contains Si, Cr, and N as main components, and further wherein 
 one of the first resistive film or the second resistive film has a positive TCR value, and the other has a negative TCR value, and 
 the first resistive film and the second resistive film contain different percentages of silicon nitride across xTCR (a threshold of silicon nitride) as a boundary, the xTCR being a percentage of silicon nitride at which a positive TCR changes to a negative TCR or a negative TCR changes to a positive TCR. 
 
     
     
       2. The thin-film resistor according to  claim 1 , wherein the second resistive film contains added thereto at least one metal element selected from Ti, Zr, or Al. 
     
     
       3. The thin-film resistor according to  claim 2 , wherein the at least one metal element added is contained at a percentage of 1 to 4 atm % relative to an entirety of the second resistive film. 
     
     
       4. The thin-film resistor according to  claim 1 , wherein
 the first resistive film contains Si, Cr, and N as main components, and the second resistive film contains Si, N, and a metal element that is to form silicide but is unlikely to form nitride. 
 
     
     
       5. The thin-film resistor according to  claim 2 , wherein the at least one metal element comprises at least one element selected from Mo, W, Fe, or Co. 
     
     
       6. A method for producing a thin-film resistor including a substrate, a pair of electrodes formed on the substrate, and a resistive film connected to the pair of electrodes, the method comprising:
 forming a first resistive film containing Si, Cr, and N as main components; 
 forming a second resistive film containing Si, Cr, and N as main components in a stacked manner on the first resistive film; and 
 performing a thermal treatment at a temperature above 750° C. to adjust TCR values of the first and second resistive films substantially equal to zero, wherein 
 the first resistive film and the second resistive film are formed by sputtering in an atmosphere containing nitrogen, wherein a flow ratio of nitrogen is between 10 to 30%, and 
 a mixture ratio of the nitrogen is increased in forming one of the first resistive film or the second resistive film. 
 
     
     
       7. A thin-film resistor comprising a substrate, a pair of electrodes formed on the substrate, and a resistive film connected to the pair of electrodes, wherein
 the resistive film includes a first resistive film and a second resistive film, the second resistive film having a different TCR from that of the first resistive film, and 
 each of the first resistive film and the second resistive film contains Si, Cr, and N as main components, and further wherein 
 each of the first resistive film and the second resistive film contains silicon nitride, and 
 a percentage of Si that forms silicon nitride in the first resistive film relative to the entire Si contained in the first resistive film is less than or equal to 63%, and a percentage of Si that forms silicon nitride in the second resistive film relative to the entire Si contained in the second resistive film is greater than or equal to 68%.